Method of making a striated support for filaments



METHOD OF MAKING A STRIATED SUPPORT FOR FILAMEN'IS Original Filed March 24, 1967 Dec. 15, 1970 H. J. GREEN, JR

2 Sheets-Sheet 1 FIG. 2

FIG. 3

R u m E V WJ VI R R A H Dec. 15, 1970 1 R N, JR 3,548,045

METHOD OF MAKING A STRIATED SUPPORT FOR FILAMENTS Original Filed March 24, 1967 2 Sheets-Sheet 2 FIG. 6

INVENTOR. HARRY J GREEN, JR.

United States Patent F 3,548,045 METHOD OF MAKING A STRIATED SUPPORT FOR FILAMENTS Harry J. Green, Jr., Rochester, N.Y., assignor, by mesne assignments, to Nemonic Data Systems, Inc., Denver, Colo., a corporation of Delaware Original application Mar. 24, 1967, Ser. No. 625,771, now abandoned. Divided and this application Oct. 17, 1969, Ser. No. 867,345

Int. Cl. C04b 35/00 US. Cl. 264-104 3 Claims ABSTRACT OF THE DISCLOSURE A substrate for mounting filaments in close, accurately spaced, parallel array. A soft wire is carefully wound upon a mandrel with successive turns tightly packed against each other. Replicas of plastic or other materials are made of the surface formed by the wire. The filaments to be supported are laid in the grooves in the replicas.

BACKGROUND OF THE INVENTION This application is a divisional application of a copending patent application Ser. No. 625,771, filed on Mar. 24, 1967, and now abandoned.

BRIEF SUMMARY OF THE INVENTION There has been much recent inerest in thin film magnetic memory devices of the type including filaments such as wires coated with thin films of magnetic material, typically applied by electrolysis or evaporation in vacuo. The filaments are typically about .004 to .005 inch in diameter, and the thin film magnetic material is typically about one micron thick. The output signals produced in the operation of devices of this type are relatively small, typically on the order of a few millivolts, and it is important to achieve a high degree of uniformity in the spacings between successive wires when they are arranged in parallel array to form a matrix, otherwise variations in coupling between adjacent wires at different points along their lengths may tend to introduce errors into the system. Also, to minimize certain deleterious effects due to magnetostriction, it is desirable to provide firm support for the wires that carry the thin film magnetic material.

- Finally in the interest of space conservation, it is desirable to space the wires as closely together as possible.

Briefly, a substrate in accordance with the invention comprises a replica of the surface formed by winding a soft metal wire upon a flat mandrel with each successive reach of the wire straightened by stretching and carefully forced against the preceding reach. A master mold is made from the mandrel, and the substrates are cast in the master mold. Alternatively, more complex replication techniques may be used such as, for example, techniques applied in the production of phonograph records and of optical diffraction gratings. As many of the replicas as desired may be secured together to form a relatively large substrate. Typically, the replica is made of an insulating material such as a thermosetting resin, and an electrically conductive plate may be molded into the replica to provide an electrical ground plane.

DETAILED DESCRIPTION A presently preferred embodiment of the invention will now be described in detail in connection with the accompanying drawing, wherein:

FIG. 1 is a fragmentary isometric view of a mandrel partly wound with wire, indicating an initial step in the manufacture of a substrate according to the invention;

FIG. 2 is a cross-section taken along the line 22 of FIG. 1;

3,548,045 Patented Dec. 15, 1970 FIG. 3 is a cross-sectional view of a mold according to the invention, illustrating casting of a substrate;

FIG. 4 is a partly schematic diagram in isometric form of the assembly of individual units according to the invention to form a relatively large substrate.

FIG. 5 is a perspective view on a larger scale than FIG. 4 of a support according to the invention;

FIG. 6 is a cross-sectional view of a support generally similar to the one shown in FIG. 5, but without a conductive ground plane; and

FIG. 7 is a cross-sectional view of the support shown in FIG. 5.

Referring now to the drawing, a substrate unit 10 is in the form of a replica of a master mold 12, which is made by winding a soft wire 14 upon a mandrel 16, the significant surface 18 of which has been carefully finished to a high degree of flatness. To insure that the wire 14 lies flat upon the mandrel, the edges of the mandrel around which the wire is turned are rounded over a relatively long radius such that the Wire will readily accept the curvature. The wire 14, which may be, for example, of copper, is straightened by stretching either just prior to winding or as it is wound. The winding is carefully done, and each turn of the wire is forced against the preceding one so that it lies in abutting engagement with it. After winding, the mandrel with the wire 14 upon it is carefully inspected to insure that the wires are straight and true, free of foreign matter, and lie flat upon the mandrel. If desired, the mandrel may be first coated with a film of an adhesive material to secure the wire 14 firmly upon it. Molds 20 are then made by casting upon the mandrel. The molds 20 may be made of any desired casting material such as certain silicone compositions, many of which have been specially developed for use in dentistry, and which are capable of forming accurate negative images of the surface formed by the wire 14.

The molds 20 are then used to produce replicas 10 of the original master mold 12. The replicas 10 are typically cast of an insulating thermo-setting resin selected from among those having good dimensional stability. For certain uses, it is desired to provide a sheet of conductive material, called a ground plane, closely adjacent to, but insulated from, the wires of the magnetic memory. For this purpose, after the mold 20 is partly filled with the insulating material that is used to form the replica 10, a sheet 22 of conductive material is placed in the mold and pushed down until it comes into contact with and rests on the lands 24 of the mold. The balance of the mold is then filled with the insulating casting material, which is then hardened to form a rigid substrate for the Wires of the magnetic memory or any other filaments.

The replicas 10 can readily be made with a high degree of accuracy, that is, with very small deviations from the shapes and dimensions of the surface of the wire 14 on the mandrel. For all practical purposes, the replicas are exact copies of the face. If reasonable care is exercised in winding the wire 14 upon the mandrel 12, a large number of individual replicas 10 may readily be arrayed in uniform registration to form an overall memory plane of any desired size. Each replica 10 is identical to the next one, and alignment and registration problems are, therefore, minimized.

Another advantage in the practice of the invention relates to the cross-sectional shape of the grooves. The grooves are generally V-shaped in cross-section so that the wires, or other filaments laid in them are urged toward and held in centered alignment with the grooves with a high degree of uniformity and precision.

What is claimed is:

1. Method of making a striated support for filaments or the like comprising:

(a) winding a wire upon a mandrel having a flat sur- 4 face so that successive turns of the wire lie in References Cited iitiaisgulitfapgrgggl, and abutting engagement upon the UNITED STATES PATENTS (b) making a positive replica composed of insulating 1,757,543 5/1930 4 material of the exposed surface portions of the wire 2,056,415 10/1936 Young 16 45 5 3,019,125 1/1962 Eggenberger et a1 117-8 WhlCh he on the fiat surface of the mandrel.

2. Method according to claim 1 including the step of 3,098,262 7/1963 Wlsotzky 264227X including a sheet of conductive material in the replica 3241429 3/1966 f" et 264 1X with its outermost surface approximately coincident with 3,414,972 12/1968 Reld et 29 604 the cusps formed between successive striae on the sur- 3,457,634 7/1969 face of the replica. 10 2,562,078 7/1951 Wlnnek.

3. Method of making a striated support for filaments FOREIGN PATENTS ("the llke compnsmg: 903,633 12/1953 Germany.

(a) laying down successive lengths of a round wire in straight, parallel, and abutting relationship upon a 15 JOHN CAMPBELL, Primary EXamiIleI flat surface, each of said lengths contacting said sur- 3 c REI Assistant Examiner face, and (b) making a positive replica composed of insulating material of the exposed surface of the Wire. 29-5274, 604; 264227 

